In recent years, trends toward finer pattern designing of solid-state image pickup devices have been advancing. With the trends, a copper interconnect which allows finer interconnection is beginning to be applied to solid-state image pickup devices.
PTL 1 discloses a solid-state image pickup device including copper interconnects and having a configuration in which antidiffusion films for the copper interconnects are not arranged above each photoelectric conversion element.
PTL 2 discloses a back side illumination solid-state image pickup device including a substrate that includes a pixel portion provided with photoelectric conversion elements and signal reading circuits and a substrate that includes peripheral circuits driving the circuits in the pixel portion and processing read signals, the substrates being joined to each other.
In the configuration disclosed in PTL 1, copper may diffuse into the photoelectric conversion element because the diffusion coefficient of copper is extremely high. Assuming that the surface of each copper interconnect is protected using the antidiffusion film, for example, after a layer containing copper is formed on the same substrate, copper may diffuse from the end surfaces or the rear surface of the substrate. If an impurity, such as copper, is incorporated into a semiconductor region which constitutes the photoelectric conversion element, the copper incorporation causes dark current or leakage current. Disadvantageously, for example, a white defect occurs in image data.